PUBLIC MARKS with tags données & "Récupération de données"

At a regular pace, we hear about social networks catastrophes. One of the last example is the bookmark service Magnolia which has lost all data from its users. Some people who have subscribed to their own RSS feed of bookmarks have recovered their data. Social networks catastrophes are of a different types and with different consequences, but often revolve around personal data. These data can be "fully" private to completly public with a lot of granularity in between (an opacity defined by shades).